790
FXUS61 KPHI 162134
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
534 PM EDT Fri May 16 2025

.SYNOPSIS...
Periods of showers, thunderstorms, and humidity continue
through Saturday morning ahead of a strong cold front that
passes through Saturday afternoon into Saturday evening. High
pressure builds into the area on Sunday and persists into
Tuesday before another period of unsettled weather returns
Wednesday into Thursday.

&&

.NEAR TERM /THROUGH SATURDAY/...
530 PM update...
Severe Thunderstorm Watch in effect for central and southern
areas as next incoming MCS moving toward region presently.
Severe warnings may be imminent for southern areas, though
uncertainty about how far north and east activity can maintain
strength given how well worked over the atmosphere was and
because we`re about to lose daylight.

4PM discussion...
A second round of severe weather is possible late this
afternoon and into tonight as another MCS moves east from the
southern Ohio River Valley across Virginia and into the DC
Metro. This MCS is expected to bring a cluster of storms across
the Delmarva tonight, potentially impacting portions of
southeast PA and southern NJ again. This MCS also looks to
interact with the residual outflow boundary from our severe
storms late this morning and early this afternoon. In fact,
convection has fired up along this outflow boundary already
across central PA. There remains ample untapped instability
(2000-3000 J/kg CAPE) across south central PA, northern VA, and
the western Delmarva Peninsula. Furthermore, skies have cleared
out rapidly this afternoon, allowing for some locations to see
some atmospheric destabilization again. Damaging wind gusts with
some possible hail will be the main concerns, but another
tornado or two cannot be ruled out with this second round of
severe storms. The second round of severe potential will be
around 5-9pm.

Overnight, there may still be some convection ongoing into the
evening but this should diminish with time leading to another
brief lull. Once again, there could be some low clouds, mist,
and fog that form due to the continuing moist environment. The
action won`t be over though because another decaying MCS may
move into the area sometime overnight into early Saturday
morning. There remains a lot of uncertainty on this though and
depends on how storms pan out across Missouri and Kentucky
tonight. Otherwise, it will be a mild, muggy night with lows
mainly in the 60s.

The aforementioned MCS arrives across the region around
daybreak. A bit of uncertainty still remains with how strong
this MCS will remain by the time it reaches the Delaware Valley,
but the chance for showers and storms certainly remains
possible. Skies should be partly to mostly cloudy through the
morning however, before clearing out by early afternoon.
Temperatures will climb into the 80s for most areas with dew
points in the low to mid 60s making it feel quite uncomfortable
outside. The cold front will continue to make its way east
through the afternoon where isolated to scattered thunderstorms
will re-develop by the afternoon. That said, the latest guidance
is less aggressive with storm development Saturday afternoon.
While some instability will be around, upper level forcing will
be weaker and drier air aloft may limit any widespread
convective initiation. As of now, storms tomorrow will likely be
more isolated to scattered in nature with a marginal chance for
storms to become severe. If so, gusty winds and hail will be the
main concern.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
The cold front will push off the coast by Saturday night and
the threat for storms wanes in addition to the loss of daytime
heating. Nighttime lows will be in the mid 50s to low 60s.

Sunday is looking like the better half of the weekend as tranquil
weather returns with the upper trough moving further east. Partly to
mostly cloudy skies are expected with dry conditions and lower
humidity. Perhaps an isolated shower is possible north and west, but
general thinking is most of the area will stay dry. The one thing to
note is winds will increase as diurnal mixing occurs as the area
lies wedged between systems resulting in a tightening pressure
gradient. Wind gusts up 30-35 mph will be possible. Gusts will
diminish into Sunday night under mostly clear skies. Despite the
windy conditions, high temperatures should mainly be in the 70s
(with 60s in the Poconos).

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
By Monday, low pressure over the Canadian Maritimes will begin to
move further east into the North Atlantic. At the same time, high
pressure will settle over the Mid-Atlantic before moving offshore on
Tuesday. Aloft, the area will be situated under northwest flow in
wake of exiting upper trough. All in all, a tranquil weather period
is in store with mostly clear skies, light winds and dry weather.

By Tuesday night and through the middle of the week, our attention
will turn to our next weather system which will take aim at the
area. Global and ensemble guidance both feature a deep upper trough
moving into the Great Lakes/Northeast region around the middle of
the week with a potential coastal low developing before moving up
towards New England. This would indicate another period of unsettled
weather with periods of rain starting as early as Tuesday night,
and more so on Wednesday and Thursday. Still quite a ways out from
this potential, so have generally stuck with NBM guidance and capped
rain chances at chance (~30-50%).

In terms of temperatures, we`ll encounter temperatures around
average on Monday, before dipping below average for Tuesday through
Thursday as the area remains situated within the deep upper
trough.

&&

.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Rest of today...A lull in showers and thunderstorms this
afternoon before another round of storms may arrive late
afternoon and early evening. Second round will mainly impact
all terminals except ABE. Skies will be mostly clear, but a low
scattered deck may cause brief moments of MVFR/IFR conditions
right over the terminals. Generally S to SSE flow less than 10
kts for the rest of the afternoon, but stronger gusts in
thunderstorms.

Tonight...Any showers/storms diminish through the evening with
with the potential for low cigs and low visbys once again due to
stratus, mist and fog. Low MVFR or IFR appears likely. More
showers and storms could move in late. S to SW winds around 5
knots. Low confidence.

Saturday...Sub VFR conditions possible early in the morning with
showers and storms around. Otherwise, primarily VFR expected.
Isolated to showers and thunderstorms possible in the afternoon afternoon
and early evening. Winds WSW around 10-15 kts with gusts to 20
kts. Low confidence on showers and storms in the morning;
moderate confidence otherwise.

Outlook...

Saturday night...VFR. Winds W to WNW 10 kts or less.

Sunday through Tuesday...VFR. Gusty winds up to 25-30 kt possible on
Sunday. Otherwise, no significant weather expected.

&&

.MARINE...
Generally sub SCA except storms tonight into early Saturday
morning could produce locally strong winds.

A few isolated showers and storms possible Saturday afternoon.
SW winds gust to around 15-20 kts in the afternoon, but no
headlines expected.

Outlook...

Saturday night...No marine headlines expected.

Sunday through Sunday night...SCA conditions possible due to wind
gusts up to 25 kt.

Monday through Tuesday...No marine headlines expected.

Rip current...
Currently projecting low risk of rip currents over the weekend
based on low wave heights of 1-2 feet and winds shifting
offshore at 10-15 mph.

&&

.TIDES/COASTAL FLOODING...
The Coastal Flood Advisory for northwestern Burlington and lower
Bucks Counties has been extended until 8 AM Saturday. Minor
coastal flooding is expected with the early morning high tide
this morning and on Saturday. It`s possible minor coastal
flooding may occur on Sunday as well, where further extensions
may be needed.

For areas of the lower tidal Delaware River near Philadelphia
may encounter spotty minor coastal flooding through Saturday,
but should fall short of advisory levels.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Coastal Flood Advisory until 8 AM EDT Saturday for PAZ106.
NJ...Coastal Flood Advisory until 8 AM EDT Saturday for NJZ019.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...MJL
NEAR TERM...Fitzsimmons/MJL/RCM
SHORT TERM...DeSilva
LONG TERM...DeSilva
AVIATION...DeSilva/Fitzsimmons
MARINE...DeSilva/Fitzsimmons/RCM
TIDES/COASTAL FLOODING...